William k cosgeoye



2 Sheets.-Sheet 11 W. N. OOSGROVE.

(NoModeL) GRINDING MILL. No. 248,578. Patented Oct. 25,1881.

N PETERS, Pholoiithograpiwn Washinglon. n. cy

(No Model.) 2 Sheets-Sheet 2.

W. N. OOSGROVE.

GRINDING MILL.

No. 248,578. Patented Oct. 25,1881.

NITED STATES PATENT OFFIQE. F

WILLIAM N. GOSGROVE, OF FARIBAULT, MINN., ASSIGNOR OF ONEJIALF TO WILLIAM TENNANT AND ROBERT MORRILL, BOTH OF SAME PLACE.

GRlNDiNG-MILL.

SPECIFICATION forming part of Letters r atent No. 248,578, dated October 25, 1881.

Application filed March 17, 1881. (No model.)

To all whom it may concern:

Beit known that I, WILLIAM N. Ooseaovn, of Faribault, in the county of Rice and State of Minnesota, have invented certain new and useful Improvements in Grinding Mills; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanyingdrawings,forming part of this specification, in which- Figure lrepresents a side elevation of the machine with a portion of the casing broken away; Fig.2, a rear view with the rear casing removed; and Fig. 3, a detail view, showing the construction of the screens or sieves and the manner of adjusting them with respect to the brushes.

The same letters of reference in the several figures denote the same parts.

This invention relates to that class of grinding-mills in which the grain is subjected to repeated grindings or reductions by successive pairs of co-operating grinding-rolls, and in which the fine flour and middlings are separated and removed from the product of each grinding or reduction and the remaining portions of such product passed to thenext pair of rolls, and so on throughout the machine.

The invention consists in the improved construction of certain parts of the mill, and in the several novel combinations and sub-combinations which I will now proceed to describe.

In the drawings, a represents the hopperinto which the grain to be ground is fed; a, a feed-roller working in the lower part of the hopper; a a hinged or swinging gate, hung on journals at opposite ends of the hopper and co-operating with the roller a to regulate the feed of the grain from the hopper, as will be hereinafter more particularly described; 0?, a screw for adjusting the gate a 1) 11 represent the first pair of grinding-rolls; 0, a revolving fan, onto which the product of the first grinding falls; (1, a concave screen or sieve partially surrounding the fan; 6, openings in the casing for the admission of air to the fan; f, a trunk into which the fine flour and middlings are forced through the screen by the operation of the fan; g, an inclined deflector for directingthe fine flour and middlin gs into said trunk; h, perforations in the inclined deflector for the admission of air 5 i, an exhaustfan for drawing out of the trunkfthe fine, light dust and forcing it to a suitable dust-receiver for subsequent treatment.

b b are the second pair of grinding-rolls, to which the product of the first grinding is delivered by the revolving fan 0. Below this second pair of rolls is arranged another fan and its co-operating sieve and deflector, and below them again a third pair of rolls, and so on throughout the machine, as many pairs of rolls, fans, 860., being employed as may be desired or found necessary. jis a conveyer at the bottom of the machine, to which the separated fine flour and middlings pass by gravity from the trunk f, and to which also the 'product of the last grinding is delivered.

One of the rolls of each pair is provided with a pulley, k, and is preferably revolved by means of a belt, I, which passes over all said pulleys and also over lap-pulleys m, and is driven from a main driving-pulley, a, as shown. A tightening-pulley, a, is employed to give proper tension to the belt.

The shafts of the fans are provided with pulle s o, and are in turn driven by means of belts 19 passing around said pulleys,and also around other pulleys, g, on the opposite ends of the lappulley shafts.

The shaft of the pulley-roll of each pair of the rolls is provided with a gear, 1", which meshes with a smaller gear, 8, on the shaft of the co-operating roll, so as to cause a differential motion of the two rolls. The difference in the speed of the two rolls can be regulated as desired.

I have found by actual test of a machine containing five pairs of rolls, each of a diameter of ten inches and a length of thirty-six inches, that excellent results can be obtained by giving the rolls of the first two pairs a relative speed of two and one-half to one; the rolls of the third pair a relative speed of two and onefourth to one; the rolls of the fourth pair a relative speed of two to one, and the rolls of the fifth or last pair a relative speed of one and one-half to one; and I recommend that substantially these relative rates of speed be followed. A single change of gears will,however, enable the relative speed to be altered, as will be readily understood.

The shafts of the rolls of each pair are journaled in boxes, as shown, and one roll is preferably adapted to be adjusted nearer to or farther from the other by means of adjustin gscrews t applied to its boxes in order that the material may be ground more or less fine, and that the process of grad ual reduction may beeffectually carried out. The grinding-rolls may be plain or corrugated, though I prefer them corrugated. The corrugations may be form ed in any suitable manner, butI recommend that they be formed by grooving the rolls spirally, as such form of dress I have found by practice to operate admirably.

Any suitable form of fan may be employed to effect the separation ofthe ground product. In the drawingslhave shown three forms, one (*the upper or first one) consisting merely oftwo pulleys or heads mounted on the shaft, to which are attached, at suitable distances apart, longitudinal strips or bars carrying brushes a, which project against or in close proximity to the screens; another (the second) cousistin g of the same arrangement, with the addition of blades '0 between the brush-strips; and another (the third or lower one) in which blades only are used, the brushes being entirely omitted. Any or all of these forms of fan, or any other suitable form, may be employed. I prefer, however, to employ the form in which both blades and brush-strips are provided, as not only is a blast of air produced and forced through the screen by such an arrangement, but the screen or sieve is also kept clear by the sweeping action of the brushes. The screens or sieves may be of any suitable material, but are preferably made of steel wire woven to the proper mesh. The frames in which they are placed are preferably made in sections hinged together, as shown in Fig. 3, and provided with slots and adjusting-screws to enable the screens to be adjusted nearer to or farther from the fans, as occasion may require.

Heretofore in machines of this class it has been customary to employ, in connection with a revolving roller in the bottom of the grain hopper, a sliding gate capable of adjustment to and from the roller tangentially, so as to regulate the slit or aperture through which the grain passes; but such arrangement is defective, because when the machine stops any grain remainingin the hopper passes out by its own gravity through the oblique discharge-opening and lodges between the rolls, thereby clogging said rolls, so that when the machine is again started up the belts will run off, thus causing much annoyance and delay.

In my improved feeding arrangement the edge of the swinging gate stands at or near the center of the roller, and consequently the feed takes place through a lateral instead of an oblique opening, and when the rollerceases to rotate the feed also ceases, because the weight of the grain in the hopper alone is not sufficient to force out the grain through such lateral opening unassisted by the action of the feed roller. The gate is arranged so as to rated and forced out through the screen by the contact of the fan and the air-blast produced thereby, and into the trunk f, While the remaining material is carried by the fan over the screen and falls onto the next pair of rolls. A portion of the current induced by the exhaust-fan at the top of the trunk draws through and cools the descending coarse material, and passes in through the openings in the inclined deflector and through the flour and middlings, and, assisted by currents from the several separating-fans, carries off up through the trunk all the fine light dust from the flour and middlings, and conveys it to a dust-receiver of any approy'ed form. The rolls of the second pair are adjusted a little nearer together than those of the first pair, and the material falling upon them is by them still further reduced and falls upon the second fan, which acts upon it in a manner similar to the first fan. Continuing through the mill, the material is subjected to still further reductions and separations, until it finallyfalls onto the conveyer at the base of the mill, where, mingling with the flour and middlings descending through the trunkf, the whole is conveyed 011' and elevated to the separators or purifiers for further treatment.

In the arrangement shown in the drawings the flour and middlings from all the screens and fans are delivered into a common trunk with a single exhaust at the top. It is obvious, however, that instead of such arrangement separate trunks may be provided for each screen and fan, and a separate exhaust provided for each trunk.

The separating-fans should be of a size and driven at a rate of speed proportioned to the size and speed of the grinding-rolls, so as to properly and effectively act upon the product of each grinding without, on the one hand, allowing it to accumulate or back up, and, on the other hand, carrying it 011' too fast. I recommend that for use in connection with rolls ten inches in diameter said fans be made about thirty inches in diameter, and that the screen or sieve be of the proper relative size. Inasmuch as the product of the first grinding is comparatively coarse and contains but little fine flour and middlings, and as the yield of fine flour and middlings from each successive grinding is greater by reason of the greater reduction, Irecommend, also, that each successive separating-brush be made somewhat larger than its predecessor, and that a screen of increased area be provided for it, in order that the capacity of the separating means may be increased in proportion as there is an increase in the amount of material to be separated.

It will be observed that by the arrangement of grinding-rolls, separating-fans, screens, &c., in the manner herein described and shown, the passage of the material through the mill is effected almost entirely by gravity, all elevating and-conveying machinerybeingdispensed with between the several reductions.

While I have described the operation of the mill upon wheat alone, it is evident that it is also adapted to the grinding of middlings as well. When so used plain smooth rolls are employed instead of corrugated ones.

Having thus described myinvention, I claim as new-- 1. In a grinding-mill, the combination, with two or more pairs of grinding-rolls, the rolls of each pair of which run at differential speed, of a revolving separating-fan between each pair of rolls and the next succeeding pair of rolls, and a concave screen or sieve co-operating with each fan, whereby the ground product is delivered directly onto the fans, which operate to force the fine flour and middlings out through the screens and to deliver the remaining material to the next pair of rolls for further reduction, substantially as described.

2. In a grinding-mill, the combination, with two or more pairs of grinding-rolls, the rolls of each pair of which run at differential speed, witha revolving fan between each' pair of rolls and the rolls of the next succeeding pair, having both blades and brushes, and a concave screen or sieve co-operating with each fan, substantially as described.

3. In a grinding-mill,the combination of two or more pairs of grinding-rolls, the rolls of each pair of which run at differential speed, with a revolving fan between each pair of rolls and the rolls of the next succeeding pair, and onto which the ground product is directly delivered, concave screens or sieves co-operating with the fan, an air-trunk,into which fine flour and middlings forced through the screens are delivered, and an exhaust for drawing off the fine dust from said trunk, substantially as described.

4. In a grinding-mill, the combination, sub- I stailtially as described, of the two or more pairs of grinding-rolls, the rolls of each pair of which run at differential speed, the revolving fans and screens arranged between each pair of rolls and the next succeeding pair, the air-trunk, into which the separated flour and middlin gs are delivered, perforatedinclined deflectors for directing the material into said trunk, and an exhaust at the top of the trunk, whereby a current of air is made to pass through the coarse material as it falls from each fan to the next pair of rollsto cool it, and whereby, also, the fine dustis drawn out of the trunk and delivered to a suitable dust-receiver for further treatment. I

5. In a grinding-mill, the combination, substantially as described, of the several pairs of grinding-rolls, the rolls of each pair of which move at difl'ercntial speed, the concave screens between each pair of rolls and the rolls of the next succeeding pair, the rotating separatingfans, onto which the ground material is directly delivered, and by which the finefiour and middlings are forced out through the screens and the remaining material delivered directly to the next pair of rolls, with the trunk, into which the fine fiour and middlin gs are delivered, the exhaust, and the conveyor at the bottom of the machine, all said parts being combined to operate substantially in the manner described.

6. In a grinding-mill, the combination, with the revolving separating-fans, of the co-operating screens, each composed of two half-sec tions, and rendered adjustable toward and from the fans by means of the slots and set-screws, substantially as described.

WILLIAM N. GOSGROVE.

Witnesses:

J OSEPH FORREST, WM. A. BLAGKSTOOK. 

